Neutron-diffraction study on the field dependent magnetic ordering in Co—Cu superlattices

Abstract

We have studied Co—Cu single crystal superlattices by neutron diffraction and bulk magnetization measurements. Special care was paid to the proper orientation of the sample for the magnetization experiments, in order to distinguish between in-plane anisotropies. Neutron diffraction data shows a pattern from the new superstructure (periodicity Λ SL), as well as a second diffraction pattern of magnetic origin with 2Λ SL periodicity. The antiferromagnetic (AF) ordering was confirmed by polarized neutron diffraction. There is a peculiar dependence on the applied external field. At moderate magnetic fields (6–8 kOe), the AF alignment is reversed to ferromagnetic. For lower magnetic fields, there is a complicated magnetic behavior, with strong competition between in-plane anisotropies and exchange coupling energy, which produce intermedium magnetic orderings.